January 10th, 2020

Mars moon got its grooves from rolling stones, study suggests

Groovy Phobos: Much of Phobos’ surface is covered with strange linear grooves. New research bolsters that idea the boulders blasted free from Stickney crater (the large depression on the right) carved those iconic grooves. NASA/JPL-Caltech/University of Arizona

A new study bolsters the idea that strange grooves crisscrossing the surface of the Martian moon Phobos were made by rolling boulders blasted free from an ancient asteroid impact.

The research, published in Planetary and Space Science, uses computer models to simulate the movement of debris from Stickney crater, a huge gash on one end of Phobos’ oblong body. The models show that boulders rolling across the surface in the aftermath of the Stickney impact could have created the puzzling patterns of grooves seen on Phobos today.

“These grooves are a distinctive feature of Phobos, and how they formed has been debated by planetary scientists for 40 years,” said Ken Ramsley, a planetary science researcher at Brown University who led the work. “We think this study is another step toward zeroing in on an explanation.”

Phobos’ grooves, which are visible across most of the moon’s surface, were first glimpsed in the 1970s by NASA’s Mariner and Viking missions. Over the years, there has been no shortage of explanations put forward for how they formed. Some scientists have posited that large impacts on Mars have showered the nearby moon with groove-carving debris. Others think that Mars’ gravity is slowly tearing Phobos apart, and the grooves are signs of structural failure.

Still other researchers have made the case that there’s a connection between the grooves and the Stickney impact. In the late 1970s, planetary scientists Lionel Wilson and Jim Head proposed the idea that ejecta — bouncing, sliding and rolling boulders — from Stickney may have carved the grooves. Head, a professor in Brown’s department of Earth, Environmental and Planetary Sciences, was also a coauthor of this new paper.

December 11th, 2019

NASA’s Treasure Map for Water Ice on Mars

The annotated area of Mars in this illustration holds near-surface water ice that would be easily accessible for astronauts to dig up. The water ice was identified as part of a map using data from NASA orbiters.
Credits: NASA/JPL-Caltech

NASA has big plans for returning astronauts to the Moon in 2024, a stepping stone on the path to sending humans to Mars. But where should the first people on the Red Planet land?

A new paper published in Geophysical Research Letters will help by providing a map of water ice believed to be as little as an inch (2.5 centimeters) below the surface.

Water ice will be a key consideration for any potential landing site. With little room to spare aboard a spacecraft, any human missions to Mars will have to harvest what’s already available for drinking water and making rocket fuel.

NASA calls this concept “in situ resource utilization,” and it’s an important factor in selecting human landing sites on Mars. Satellites orbiting Mars are essential in helping scientists determine the best places for building the first Martian research station. The authors of the new paper make use of data from two of those spacecraft, NASA’s Mars Reconnaissance Orbiter (MRO) and Mars Odyssey orbiter, to locate water ice that could potentially be within reach of astronauts on the Red Planet.

“You wouldn’t need a backhoe to dig up this ice. You could use a shovel,” said the paper’s lead author, Sylvain Piqueux of NASA’s Jet Propulsion Laboratory in Pasadena, California. “We’re continuing to collect data on buried ice on Mars, zeroing in on the best places for astronauts to land.”

November 12th, 2019

With Mars Methane Mystery Unsolved, Curiosity Serves Scientists a New One: Oxygen

Credits: Melissa Trainer/Dan Gallagher/NASA Goddard

For the first time in the history of space exploration, scientists have measured the seasonal changes in the gases that fill the air directly above the surface of Gale Crater on Mars. As a result, they noticed something baffling: oxygen, the gas many Earth creatures use to breathe, behaves in a way that so far scientists cannot explain through any known chemical processes.

Over the course of three Mars years (or nearly six Earth years) an instrument in the Sample Analysis at Mars (SAM) portable chemistry lab inside the belly of NASA’s Curiosity rover inhaled the air of Gale Crater and analyzed its composition. The results SAM spit out confirmed the makeup of the Martian atmosphere at the surface: 95% by volume of carbon dioxide (CO2), 2.6% molecular nitrogen (N2), 1.9% argon (Ar), 0.16% molecular oxygen (O2), and 0.06% carbon monoxide (CO). They also revealed how the molecules in the Martian air mix and circulate with the changes in air pressure throughout the year. These changes are caused when CO2 gas freezes over the poles in the winter, thereby lowering the air pressure across the planet following redistribution of air to maintain pressure equilibrium. When CO2 evaporates in the spring and summer and mixes across Mars, it raises the air pressure.

Within this environment, scientists found that nitrogen and argon follow a predictable seasonal pattern, waxing and waning in concentration in Gale Crater throughout the year relative to how much CO2 is in the air. They expected oxygen to do the same. But it didn’t. Instead, the amount of the gas in the air rose throughout spring and summer by as much as 30%, and then dropped back to levels predicted by known chemistry in fall. This pattern repeated each spring, though the amount of oxygen added to the atmosphere varied, implying that something was producing it and then taking it away.

October 8th, 2019

Curiosity rover finds an ancient oasis on Mars

Filled with briny lakes, the Quisquiro salt flat in South America’s Altiplano represents the kind of landscape that scientists think may have existed in Gale Crater, which NASA’s Curiosity rover is exploring. Credit: Maksym Bocharov

If you could travel back in time 3.5 billion years, what would Mars look like? The picture is evolving among scientists working with NASA’s Curiosity rover.

Imagine ponds dotting the floor of Gale Crater, the 100-mile-wide (150-kilometer-wide) ancient basin that Curiosity is exploring. Streams might have laced the crater’s walls, running toward its base. Watch history in fast forward, and you’d see these waterways overflow then dry up, a cycle that probably repeated itself numerous times over millions of years.

That is the landscape described by Curiosity scientists in a Nature Geoscience paper published today. The authors interpret rocks enriched in mineral salts discovered by the rover as evidence of shallow briny ponds that went through episodes of overflow and drying. The deposits serve as a watermark created by climate fluctuations as the Martian environment transitioned from a wetter one to the freezing desert it is today.

Scientists would like to understand how long this transition took and when exactly it occurred. This latest clue may be a sign of findings to come as Curiosity heads toward a region called the “sulfate-bearing unit,” which is expected to have formed in an even drier environment. It represents a stark difference from lower down the mountain, where Curiosity discovered evidence of persistent freshwater lakes.

July 29th, 2019

Ancient Mars tsunami hints at surprisingly wet world

Elevation changes also indicate where Mars may have once had a vast northern ocean.
Mars Orbiter Laser Altimeter Science Team/NASA

Three and a half billion years ago, an asteroid slammed into Mars. The cataclysm wasn’t terribly unusual for this period in the solar system’s history, but the fallout would leave its mark. The asteroid carved out an enormous crater. It also sent a wall of water a thousand feet high hurtling around the young Red Planet, which was much more blue at the time.

That wave then slammed into land, creating strange landforms on Mars. Since 2017, Francois Costard, a scientist at the French National Centre for Scientific Research, has been advocating this theory to explain a region called the Thumbprint Terrain, and now he thinks he may have found the crater that was ground zero for the tsunami. He published his findings June 26 in the Journal of Geophysical Research Planets.

July 24th, 2019

Hypnotic animation reveals how seismic waves travel across Mars, months after NASA’s InSight lander recorded quakes on the red planet for the first time

Scientists have simulated the path of seismic waves rippling across the red planet. The ways in which quakes look and feel differ depending on the materials they’re traversing, meaning they may act very differently than what we’re used to here on Earth, the space agency explains

Scientists have simulated the path of seismic waves rippling across the red planet.

NASA’s InSight lander detected its first marsquake earlier this year, providing on-the-ground data for the first time on the behaviors of these natural phenomena on Mars.

The ways in which quakes look and feel differ depending on the materials they’re traversing, meaning they may act very differently than what we’re used to here on Earth, the space agency explains.

A new animation shows just how this might play out beneath the surface of Mars.

June 18th, 2019

Meteors help Martian clouds form

This image, taken from a computer simulation, shows middle altitude clouds on Mars. (Courtesy Victoria Hartwick)

How did the Red Planet get all of its clouds? CU Boulder researchers may have discovered the secret: just add meteors.

Astronomers have long observed clouds in Mars’ middle atmosphere, which begins about 18 miles (30 kilometers) above the surface, but have struggled to explain how they formed.

Now, a new study, which will be published on June 17 in the journal Nature Geoscience, examines those wispy accumulations and suggests that they owe their existence to a phenomenon called “meteoric smoke”—essentially, the icy dust created by space debris slamming into the planet’s atmosphere.

The findings are a good reminder that planets and their weather patterns aren’t isolated from the solar systems around them.

“We’re used to thinking of Earth, Mars and other bodies as these really self-contained planets that determine their own climates,” said Victoria Hartwick, a graduate student in the Department of Atmospheric and Ocean Sciences (ATOC) and lead author of the new study. “But climate isn’t independent of the surrounding solar system.”

The research, which included co-authors Brian Toon at CU Boulder and Nicholas Heavens at Hampton University in Virginia, hangs on a basic fact about clouds: They don’t come out of nowhere.

“Clouds don’t just form on their own,” said Hartwick, also of the Laboratory for Atmospheric and Space Physics at CU Boulder. “They need something that they can condense on to.”

On Earth, for example, low-lying clouds begin life as tiny grains of sea salt or dust blown high into the air. Water molecules clump around these particles, becoming bigger and bigger until they form the large puffs that you can see from the ground.

But, as far as scientists can tell, those sorts of cloud seeds don’t exist in Mars’ middle atmosphere, Hartwick said. And that’s what led her and her colleagues to meteors.

June 10th, 2019

Can We Prevent Phobos’ Inevitable Demise?

Mars has two natural satellites: Deimos and Phobos; the latter orbits Mars closer than any other moon orbiting the other planets in the solar system, and it’s currently undergoing a process known as orbital decay.

In short, this means that Phobos is slowly drifting closer to Mars over time. Perhaps unsurprisingly, this has an impact on the gravitational pull between Mars and Phobos. As this tug strengthens, the tidal forces exerted on Phobos are increased, and this quite literally tears the moon apart.

Phobos’ surface is covered in strange lines, and according to planetary scientists, these are ‘stretch marks’ that result from the tidal forces that are being exerted on the moon as it orbits Mars. If the moon’s orbital decay continues at its current rate, then the moon could be destroyed in the next several million years, resulting in a planetary ring around Mars.

This raises the question: could we save Phobos from a seemingly inevitable demise? Theoretically, we could, but it wouldn’t be easy or practical.

May 28th, 2019

Curiosity Gazes Upon Noctilucent Clouds Over Gale Crater

Just imagine this scene. You’re on Mars, in Gale crater, with Curiosity. The sun has just set, and the temperature is falling rapidly. You look up. You see brilliant, wispy clouds, still sunlit even though night has fallen where you’re standing. They’re high in elevation, so the Sun can still reach them. As you stand there, skygazing, feeling increasingly chilled, the noctilucent clouds waft along in the Martian air, dimming from east to west as the Sun sets on them.

Curiosity has, in fact, been looking up after sunset recently. It’s been taking Navcam photos, and the camera’s reasonably broad field of view (45 degrees) lets it take in a lot of clouds, giving all of us back on Earth a chance to see them, too.

May 9th, 2019

New water cycle on Mars discovered

Billions of years ago, Mars could have looked like this with an ocean covering part of its surface.

Approximately every two Earth years, when it is summer on the southern hemisphere of Mars, a window opens: only there and only in this season can water vapor efficiently rise from the lower into the upper atmosphere. There, winds carry the rare gas to the North Pole. While part of the water vapor decays and escapes into space, the rest sinks back down near the poles. Researchers from the Moscow Institute of Physics and Technology and the Max Planck Institute for Solar System Research (MPS) in Germany describe this unusual Martian water cycle in a current issue of the Geophysical Research Letters. Their computer simulations show how water vapor overcomes the barrier of cold air in the middle atmosphere of Mars and reaches higher air layers. This could help to understand why Mars – unlike Earth – has lost most of its water.

Billions of years ago, Mars was a planet rich in water with rivers and even an ocean. Since then, our neighboring planet has changed dramatically: today, only small amounts of frozen water exist in the ground; in the atmosphere, water vapor occurs only in traces. All in all, the planet may have lost at least 80 percent of its original water. In the upper atmosphere of Mars, ultraviolet radiation from the Sun split water molecules into hydrogen (H) and hydroxyl radicals (OH). The hydrogen escaped from there irretrievably into space. Measurements by space probes and space telescopes show that even today water is still lost in this way. But how is this possible? The middle atmosphere layer of Mars, like Earth’s tropopause, should actually stop the rising gas. After all, this region is usually so cold that water vapor would turn to ice. How does the Martian water vapor reach the upper air layers?

In their current simulations, the Russian and German researchers find a previously unknown mechanism reminiscent of a kind of pump. Their model comprehensively describes the flows in the entire gas envelope surrounding Mars: from the surface to an altitude of 160 kilometers. The calculations show that the normally ice-cold middle atmosphere becomes permeable to water vapor twice a day – but only at a certain location and at a certain time of year.